This invention relates generally to an apparatus for use in material handling operations. More specifically, this invention relates to an apparatus for stacking bags of granulated or powdered material in a single column on a pallet or other bag supporting means.
Broadly speaking, bag stacking or palletizing machines have long been known and used as labor saving devices in the prior art. Most of these prior an machines are adapted to stack bags of material on a pallet, wherein an empty pallet is disposed on an elevator platform and raised to a maximum level to receive a first bag or layer of bags from a bag dispenser. Thereafter, the elevator platform and pallet are lowered incrementally to receive additional layers of one or more bags from the dispenser. In this manner, bags are stacked on the pallet to a desired level by the time the elevator platform reaches its lowest level of movement. Upon reaching its lowest level of movement, the filled pallet may be removed from the machine by a fork lift or transferred by means of a conveyor to a remote pick-up station. Examples of various machines which function in this manner are disclosed in the following patents: U.S. Pat. No. 4,708,564 issued to W. J. Mylrea, et al. on Nov. 24, 1987; U.S. Pat. No. 4,271,755 issued to D. I. Kintgen, et al. on Jun. 9, 1981; U.S. Pat. No. 4,260,309 issued to W. F. Lynn on Apr. 7, 1981; U.S. Pat. No. 4,426,184 issued to E. E. Boyland on Jan. 17, 1984; U.S. Pat. No. 4,024,965 issued to G. A. Marth, et al. on May 24, 1977; U.S. Pat. No. 3,624,782 issued to O. A. McPeek, et al. on Nov. 30, 1971; U.S. Pat. No. 3,688,920 issued to W. G. Frish on Sep. 5, 1972; and U.S. Pat. No. 3,164,080 issued to F. H. Miller, Jr. on Jan. 5, 1965. A problem encountered with these machines is the need for strength in the elevator mechanism and in the means employed for moving the elevator mechanism, particularly when the pallet disposed on the elevator mechanism is nearly filled with bags. Other palletizing machines which stack sheets of paper and bundles of newspapers are disclosed U.S. Pat. No. 5,051,058 issued to O. Roth on Sep. 24, 1991; U.S. Pat. No. 4,536,119 issued to L. Miaskoff on Aug. 20, 1985; and U.S. Pat. No. 4,439,084 issued to J. S. Werkeish on Mar. 27, 1984.
An exception to the machines of the previously mentioned patents is the machine disclosed in U.S. Pat. No. 4,015,732 issued to T. Beaty, Jr., et al. on Apr. 5, 1977. This machine includes a transport frame supported by a hoist frame. A vertically movable stacking frame having an encasement bottom is suspended from one end of the transport frame over a platform or conveyor upon which an empty pallet to be loaded with bags is placed. The transport frame also carries a transport conveyor for transporting bags to the stacking frame for arrangement upon the escapement bottom. With the bags so arranged on the escapement bottom, a hoist in the hoist frame lowers the transport frame so as to lower the stacking frame to a level appropriate for disposition of the bags onto the pallet or onto the highest layer of bags that have previously been deposited on the pallet, as the case may be. A pair of vertical members located on opposite ends of the stacking frame are pivotally connected on their lower ends to horizontally extended escapement members to which escapement panels, upon which the bags are disposed, are attached. The vertical members are urged toward one another by hydraulic means to force the escapement members horizontally past one another in opposite directions to draw the escapement panels apart to discharge the bags to the pallet. The vertical members are then urged apart to draw the escapement members in the opposite direction to close the panels.
The subject assembly is both complex and massive. The hoist must be sufficiently powerful to lift and lower the entire transport frame and bag conveyor in order to lift and lower the stacking head. Moreover, the stacking head is itself a complex assembly having numerous pivotally connected members necessary for working together to horizontally move the escapement panels together for closure and apart for discharging the bags.
By means of the present invention, these and other problems encountered in the use of prior art bag stacking machines and methods are substantially overcome.